Halos appear in our skies far more often than do rainbows. They
can be seen on average twice a week in Europe and parts of
the United States. The 22° radius circular halo and sundogs
(parhelia) are the most frequent.

In this HaloSim3 simulation the sun is surrounded by a 22°
halo and flanked by sundogs.
Passing through the sundogs and extending beyond them is the parhelic
circle. It sometimes encircles the whole sky at the same altitude
as the sun. Upper and lower tangent arcs
touch the 22° halo directly above and below the sun. A circumzenithal
arc is high above all. The ice
crystals pictured are those forming each particular halo.
Click
the simulation text to go to the halo.